1. Field of the Invention
The invention relates to a doctor device for applying material, such as optionally foamable substances of varying viscosity, coating substances, lacquers, adhesives, pastes, etc. to an application surface (substrate) with the doctor pressable onto the latter. Such devices are used e.g. in flat screen printing, circular screen applications and/or apparatuses for screen-free, full-surface applications, in which the width of the application surface or the extension of the doctor can be several meters. As a function of the machine type, it is possible to carry out patterning applications (printing) and/or full-surface applications (e.g. impregnation, coating, dyeing, lacquering).
2. Description of the Related Art
Considerable significance is attached to the control of the application and the setting of the application quantities. In addition, the operating and use possibilities of a machine are dependent on the doctors used. The term "doctor" is generally understood to mean a coating profile member having varied constructions. The term includes blade coating doctors, circular profile coating doctors and roll doctors.
It is known to vary the application method by modifying the angular position of the doctor device, the contact pressure and/or the type of doctor device. The result of the application is dependent on the contact pressure, the substrate material, the application material viscosity and/or the size or spatial form of the application material supplied upstream of the doctor, as well as the fitting, construction and structural size of the apparatus. The constructional, control, dimensional and operational problems encountered with these type of apparatus have not been satisfactorily solved in all respects.
Devices operating exclusively with doctor rolls are known (DE-OS 25 44 784), in which a doctor roll can be pressed against the back of a separately arranged profile strip spaced from the rolling surface of the roll. It is disadvantageous in this arrangement that several independant components are required, which are for influencing the application result, and that a special machine type must be kept available in an adapted manner and can only be fitted, removed and cleaned separately from one another. Another known doctor device for exclusive use with a blade coating doctor (DE-OS 2 207 935) comprises a relatively solid and bulky doctor device with a rod holding the blade coating doctor and which is fixed to a support pipe. A relatively large-area lever apparatus comprising several guide and support arms is provided for modifying the angular position of the doctor device by means of a mechanical forced control. A doctor means known from WO-A-8 002 400 comprises an auxiliary mechanism with a substantially U-shaped profile having an accumulation surface for guiding magnetically pressable doctor rolls. It is proposed that the U-shaped profile be adjustably mounted in a spaced, angular manner with respect to a magnetic device positioned below an application surface. However, no specific measures for mounting the U-shaped profiles are disclosed. The only pivoting movement considered possible is about the axis of a doctor roll. For this purpose and for the purpose of vertically modifying the position of the U-shaped profile, consideration can only be given to providing a forced control for the profile as a function of the machine type used. In the case of a forced control of the type known from DE-OS 2 207 935, it is not possible or is only possible with considerable mechanical expenditure to achieve a desired, reproducible fine adjustment of an application result.